It is known that loss or failure of organs and tissues can be treated by the development of functional substitutes made by cells placed on or within matrices which can be implanted or used as extracorporeal devices.
Some reviews on this topic are: R. Langer and J. P. Vacanti; Science, 260, 920 (1993); P. E. Lacy, Scientific American, (1995) 40; W. W. Gibbs, Scientific American, (1993) 16.
Some literature reports relevant to the problem are T. R. Shockley and M. L. Yarmush, Biotechnol. Bioeng., 35 (1990) 843; M. Taya, M. Yoshikawa, and T. Kobayashi, J. Ferment. Bioeng., 67 (1989) 138; Y. Shirai, H. Heshimoto, and H. Kawahara, Appl. Microbiol. Biotechnol., 29 (1988) 113; Y. Ho and T. M. S. Chang, Artif. Organs, 16 (1992) 442; A. A. Demetriou et. al., Science, 233 (1986) 1190; F. Lim and A. M. Sun, Science, 210 (1980) 908; E. J. A. Pope, J. Sol-Gel Sci. Tech., 4 (1995) 225; E. J. A. Pope et al. "Sol-Gel Science and Technology", Volume 55 (1955) pages 33-49.
In most cases the encapsulation is performed by hydrogels, in particular polysaccaride alginate, acrylonitrile-vinyl chloride copolymers, hollow fibers, carrageenan gel, agar rods and sol-gel derived Sio.sub.2 from hydrolysis of silicon alkoxides in solution.
These approaches are affected by severe shortcomings such as reduction of mass transfer with the medium, insufficient stiffness to avoid cell release, chemical incompatibility with cell viability, production of severe poison byproducts, as for cell encapsulation by sol-gel obtained by hydrolysis and condensation of inorganic alkoxides in solution.
These problems can be solved by reacting supported cells and cell aggregates with gas-phase inorganic alkoxides suitable to react with the cell surface, resulting in a thin porous deposit of inorganic oxides in accordance with PCT application No. PCT/IT95/00083 the content of which is incorporated herewith as reference.